Effects of 3D displays: A comparison between shuttered and polarized displays

The current study investigates the effects of 3D displays (shuttered display vs. polarized display). People experienced superior fidelity and brightness when they watched 2D still images on a shuttered display, rather than on a polarized display. Conversely, people experienced greater brightness when they watched 3D still images on a polarized display, rather than on a shuttered display. Second, people were able to read a smaller font or characters on a shuttered display than on a polarized display. Third, people noticed flickering on a shuttered display when they watched 3D images. Fourth, people experienced greater brightness when they watched 3D moving images on a shuttered display, rather than on a shuttered display. The perceived brightness of the screen positively correlated with enjoyment, content satisfaction, and 3DTV satisfaction when the viewers watched a 3D movie. The flickering, on the other hand, has a negative correlation with enjoyment and 3DTV satisfaction.     

一种二维工程图向三维模型的尺寸映射算法

针对当前制造型企业内部存在二维工程图和三维CAD模型之间的数据共享问题,提出一种基于图匹配的二维工程图向三维CAD模型的尺寸映射算法,将二维工程图中的尺寸信息直接映射到对应的三维CAD模型上。首先将三维模型进行投影得到投影视图,然后将投影视图和二维工程图转化为一种空间关系图,对两个空间关系图进行图匹配,找出图元间的映射关系,并且利用工程图中尺寸标注的特点对算法进行改进,提高算法效率和可靠性。实验结果表明,该算法可以很好的实现二维工程图向三维CAD模型的尺寸映射。     

Transformations between Pictures from 2D to 3D

This paper describes programs for 3-dimensional engraving. The programs use raster or vector images to create a 3D model and, subsequently, convert this model into a sequence of control commands for 3D engraving machines. Three programs have been developed. A program for engraving general 3D surfaces from grey-scale images, a program for preparing these grey-scale images from patterns and vector images, and a program for fast 2D engraving. A simple and fast preparation of the 3D model, a user-friendly environment, and small hardware requirements were the principal goals.     

A visual simulation technique for 3D printing

Rapid prototyping technologies can create the physical part directly from the digital model by accumulating layers of a given material. Providing a tremendous flexibility of a part geometry that they can fabricate, these technologies present an opportunity for the creation of new products that cannot be made with existing technologies. One of its capabilities is to fabricate surface texture, which denotes a set of tiny repetitive geometric features on an object surface. In this paper we propose a visual simulation technique involving development of an intermediate geometric model of the surface texture design prior to fabricating the physical model. Careful examination of the visually simulated model before the actual fabrication can help minimize unwanted design iterations. The proposed technique demonstrated visualization capability by comparing the virtual model with the physical model for several test cases.     

The advance from 2D electrostatic to 3D electromagnetic particle simulation

The evolution of a 3D, E-M code from earlier less ambitious codes (and their critical analyses) is presented. The code simulates the interaction of some 10⁶ superparticles with over 10⁵ “superphotons” (field modes in k-space). Particle shaping is done in k-space, isotropically. Interpolation of the fields and their excitation is done with optimally fitted quadratic splines, using a 64³ grid. The field modes are updated with no dispersion error, the particles by a time-centered (optionally relativistic) algorithm. Data management conflicts, arising from the global nature of the field information versus the localization of particle processing, are resolved by means of the partial random accessibility of external storage. Results of trial runs with a uniform magnetised plasma show the simultaneous presence of such widely differing phenomena as Alfvén waves, Whistlers, Landau damping, trapping by electrostatic waves, etc., in the computer model.     

A simple efficient algorithm for interpolation between different grids in both 2D and 3D

Considering the importance of data transferring between different grids, we present a simple but powerful interpolation scheme using radial basis functions (RBFs) to accomplish such task in both 2D and 3D. Numerical results are presented for such interpolation between truly unstructured grids.     

Automated cell analysis in 2D and 3D: A comparative study

Optical projection tomographic microscopy is a technique that allows 3D analysis of individual cells. Theoretically, 3D morphometry would more accurately capture cellular features than 2D morphometry. To evaluate this thesis, classifiers based on 3D reconstructions of cell nuclei were compared with 2D images from the same nuclei. Human adenocarcinoma and normal lung epithelium cells were used. Testing demonstrated a three-fold reduction in the false negative rate for adenocarcinoma detection in 3D versus 2D at the same high specificity. We conclude that 3D imaging will potentially expand the horizon for automated cell analysis with broad applications in the biological sciences.     

A 3D model for ion beam formation and transport simulation

In this paper, we present a three-dimensional model for self consistently modeling ion beam formation from plasma ion sources and transporting in low energy beam transport systems. A multi-section overlapped computational domain has been used to break the original transport system into a number of weakly coupled subsystems. Within each subsystem, macro-particle tracking is used to obtain the charge density distribution in this subdomain. The three-dimensional Poisson equation is solved within the subdomain after each particle tracking to obtain the self-consistent space-charge forces and the particle tracking is repeated until the solution converges. Two new Poisson solvers based on a combination of the spectral method and the finite difference multigrid method have been developed to solve the Poisson equation in cylindrical coordinates for the straight beam transport section and in Frenet-Serret coordinates for the bending magnet section. This model can have important application in design and optimization of the low energy beam line optics of the proposed Rare Isotope Accelerator (RIA) front end.     

The comparison of accommodative response and ocular movements in viewing 3D and 2D displays

Some people often appear asthenopia symptoms of eye fatigue, double vision, nausea, and dizziness while viewing 3D movies. By testing the changes of accommodation function and ocular movements during watching 3D and 2D movies, the factors in visual discomfort are confirmed in this study.20 subjects with normal visual acuity and binocular vision function view 3D and 2D movies with the same content for 30 min, and the amplitude of accommodation, binocular vergence ability, stereo-acuity, and tear break-up time of the subjects before and after viewing the films are measured. Furthermore, an open-field auto-refractor is utilized for synchronously testing the change of accommodative response while viewing 3D and 2D films, and Skalar IRIS tracking system is applied to record ocular movements through infrared positioning.In comparison with viewing 2D movies, the accommodative response and ocular movements reveal obvious changes while viewing 3D movies. The accommodation ability and binocular vergence ability obviously drop after viewing 3D movies; moreover, the stability of stereo-acuity and tear film also gets worse. The changes of such physiological factors might be the major cause of asthenopia.     

Distance metric between 3D models and 2D images for recognition andclassification

Similarity measurements between 3D objects and 2D images are useful for the tasks of object recognition and classification. The authors distinguish between two types of similarity metrics: metrics computed in image-space (image metrics) and metrics computed in transformation-space (transformation metrics). Existing methods typically use image metrics; namely, metrics that measure the difference in the image between the observed image and the nearest view of the object. Example for such a measure is the Euclidean distance between feature points in the image and their corresponding points in the nearest view. (This measure can be computed by solving the exterior orientation calibration problem.) In this paper the authors introduce a different type of metrics: transformation metrics. These metrics penalize for the deformations applied to the object to produce the observed image. In particular, the authors define a transformation metric that optimally penalizes for “affine deformations” under weak-perspective. A closed-form solution, together with the nearest view according to this metric, are derived. The metric is shown to be equivalent to the Euclidean image metric, in the sense that they bound each other from both above and below. It therefore provides an easy-to-use closed-form approximation for the commonly-used least-squares distance between models and images. The authors demonstrate an image understanding application, where the true dimensions of a photographed battery charger are estimated by minimizing the transformation metric     

3D and 2D/3D holograms model

The estimating problem of 3D holograms orientation selectivity on angular, orthogonal, and azimuthal sensitivity parameters is formulated and solved. Tenfold increase of density 3D, 2D/3D holograms in comparison with 2D holograms at given selectivity for ones is shown in theory and experimentally.     

三维烟雾的实时模拟

提出了一种基于流体力学方程并采取欧拉法实时模拟三维真实感烟雾的算法。通过Navier-Stokes方程建立烟雾流场的物理模型,以保证视觉的真实感。为了保证运算的实时性,烟雾流场划分为三维网格空间,并将烟雾速度场的分布定义于每个立方网格单元的中心点;通过线性插值获取整幅图像中每个像素的烟雾浓度。将烟雾模拟技术用于图像的显示特技中,以产生图像消散成烟雾的视觉效果,得到了比较满意的模拟效果。     

A real-time 3D motion planning and simulation scheme for nonholonomic systems

We propose a new motion planning and simulation scheme for nonholonomic systems in this paper to provide a practical solution for these application problems taking into account of real-time obstacle avoidance and the continuous curvature path generation simultaneously in 3D unknown environment. The proposed motion planning and simulation scheme generates the motion path using a new universal Euler spiral generation algorithm, which is locally optimal based on perceived points of view. The generated Euler spiral solution can be non-symmetrical and easily implemented while maintaining a C² continuous. It is therefore more flexible and powerful in dealing with dynamic situations in real-time, compared with current symmetrical Euler spirals solutions. Real-time solutions are particularly important in navigation in unknown environments. The universal Euler spiral algorithm proposed displays a smaller maximum curvature value and smaller mean square curvature value than the conventional symmetrical algorithm in tested cases. Another significant contribution of our work is the new motion planning scheme which extend current 2D based motion planning into three-dimensional (3D) space. In this paper, we have conducted experiments and describe simulation results including 3D motion trajectory modeling for a flight simulation.     

FoamVis: visualization of 2D foam simulation data

Research in the field of complex fluids such as polymer solutions, particulate suspensions and foams studies how the flow of fluids with different material parameters changes as a result of various constraints. Surface Evolver, the standard solver software used to generate foam simulations, provides large, complex, time-dependent data sets with hundreds or thousands of individual bubbles and thousands of time steps. However this software has limited visualization capabilities, and no foam specific visualization software exists. We describe the foam research application area where, we believe, visualization has an important role to play. We present a novel application that provides various techniques for visualization, exploration and analysis of time-dependent 2D foam simulation data. We show new features in foam simulation data and new insights into foam behavior discovered using our application.     

MORI-A CPS: 3D printed soft actuators with 4D assembly simulation

Artificial Life and Robotics - Soft modular robotics combines soft materials and modular mechanisms. We are developing a vacuum-driven actuator module, MORI-A, which combines a 3D-printed flexible...     

A matching algorithm between precursory 3D process model and 2D working procedure drawing based on subgraph isomorphism

To meet the urgent requirement of enterprises for three-dimensional (3D) process models, an approach based on subgraph isomorphism is proposed to solve the matching problem between precursory 3D process model and 2D working procedure drawings. First, the projection drawings of the precursory 3D process model are obtained, then the primitives are extracted and the attributed adjacency graph (AAG) is constructed. Finally, by taking the 2D working procedure drawing as the AAG, and the projection drawing as the...     

Lateral-torsional buckling of singly symmetric web-tapered thin-walled I-beams: 1D model vs. shell FEA

This paper assesses the global performance and the underlying assumptions of a recently developed one-dimensional model characterising the elastic lateral-torsional buckling behaviour of singly symmetric tapered thin-walled open beams, which is able to account for the influence of the pre-buckling deflections. A comparative study involving the critical load factors and buckling modes yielded by (i) the one-dimensional model and (ii) two-dimensional shell finite element analyses (reference results) is presented and discussed. The results concern I-section cantilevers and simply supported beams (i) with uniform or linearly tapered webs, (ii) equal or unequal uniform flanges and (iii) acted by point loads applied at the free end or mid-span sections, respectively. In general, the one-dimensional predictions are found to agree well with the shell finite element results. Some significant discrepancies are also recorded (for the shorter beams), which are due to the occurrence of relevant cross-section distortion or localised buckling phenomena.     

通用三维服装模型的强约束动态仿真方法

随着三维游戏和虚拟试衣要求的不断提高,服装仿真已经从布料模拟向服装动态模拟的方向发展,具有真实性、实时性、通用性与交互性的服装仿真技术有很强的研究和实用价值。针对目前算法研究中普遍存在的实时性与通用性不足,提出了一种针对任意三维服装模型的实时仿真方法,将模型顶点和三角面映射为质点的弹簧模型,以克服传统的布料解算器对三维模型的网格限制。利用简便易行的Verlet积分器提高运算效率,并对质点间的形变进行强约束补偿,防止过拉伸(超弹)现象的发生,提高了系统的稳定性。通过实验验证了算法的高效性和可靠性,并可方便地以插件或模块形式与其它软件整合。     

External fixator configurations in tibia fractures: 1D optimization and 3D analysis comparison

The use of external fixation devices in orthopedic surgery is very common in open tibial fractures. A properly applied fixator may improve the healing process while one improperly applied might delay the healing process. The several external fixator systems used in clinical today, can be categorized into uniplanar–unilateral, uniplanar–bilateral, biplanar and multiplanar. The stability on the fracture focus and, therefore, the fracture healing process, is related with the type of external fixator configuration that is selected. The aim of this study is to discuss the principles for the successful application of unilateral–uniplanar external fixation, the assembly of its components, for the case of a transverse fractures using computational models. In this context, the fixation stiffness characteristics are evaluated using a simplified 1D finite element model for the tibia and external fixator. The beams are modeled with realistic cross-sectional geometry and material properties instead of a simplified model. The VABS (the Variational Asymptotic Beam Section analysis) methodology is used to compute the cross-sectional model for the generalized Timoshenko model, which was embedded in the finite element solver FEAP. The use of Timoshenko beam theory allows accounting for several kinds of loads, including torsion moments. Optimal design is performed with respect to the assembly of fixator components using a genetic algorithm. The optimization procedure is based on the evaluation of an objective function, which is dependent on the displacement at the fracture focus. The initial and optimal results are compared by performing a 3D analysis, for which different three-dimensional finite element models are created. The geometrical model of a tibia is created on the basis of data acquired by CAT scan, made for a healthy tibia of a 22 year old male. The 3D comparison of the 1D optimal results show a clear improvement on the objective function for the several load cases and, therefore, it is shown that appropriate selection of the external fixator geometrical features can lead to an improvement on the stability of the external fixator. The results obtained show that the optimal position of the side beam and the first pin should be as close as possible to the bone interface and as close as possible to the fracture focus, respectively. Concerning the second pin, it should be placed away from the first pin in case of flexion loads, to axial and torsion loads the second pin should be placed near the first pin.